This paper is a case report of individual learning support for an elementary school student who has difficulties in solving mathematical problems expressed in words. The first author instructed a boy of elementary school sixth grader. He showed difficulties in understanding mathematical problems expressed in words. To support his learning, I instructed him to solve problems expressed in words by using diagrams, and led him to use diagrams spontaneously. As a result of these instructions, he has been able to solve the problems by using diagrams spontaneously. But this spontaneous use was restricted to the problems of ratio, and was not extended to the other types of problem. It was probably because he could realize the effectiveness of using diagrams only in solving the problem of ratio. The aim of following intervention should be leading him to become aware of the effects of diagram use, and to use diagrams spontaneously when he solve various kinds of problem expressed in words.